Official repositories

A software repository is a storage location from which software packages are retrieved for installation.

Arch Linux official repositories contain essential and popular software, readily accessible via pacman. They are maintained by package maintainers.

Packages in the official repositories are constantly upgraded: when a package is upgraded, its old version is removed from the repository. There are no major Arch releases: each package is upgraded as new versions become available from upstream sources. Each repository is always coherent, i.e. the packages that it hosts always have reciprocally compatible versions.

core has fairly strict quality requirements. Developers/users need to signoff on updates before package updates are accepted. For packages with low usage, a reasonable exposure is enough: informing people about update, requesting signoffs, keeping in #testing up to a week depending on the severity of the change, lack of outstanding bug reports, along with the implicit signoff of the package maintainer.

extra

This repository can be found in .../extra/os/ on your favorite mirror.

extra contains all packages that do not fit in core. Example: Xorg, window managers, web browsers, media players, tools for working with languages such as Python and Ruby, and a lot more.

community

This repository can be found in .../community/os/ on your favorite mirror.

community contains packages that have been adopted by Trusted Users from the Arch User Repository. Some of these packages may eventually make the transition to the core or extra repositories as the developers consider them crucial to the distribution.

multilib

This repository can be found in .../multilib/os/ on your favorite mirror.

multilib contains 32-bit software and libraries that can be used to run and build 32-bit applications on 64-bit installs (e.g. wine, steam, etc).

With the multilib repository enabled, the 32-bit compatible libraries are located under /usr/lib32/.

Enabling multilib

To enable multilib repository, uncomment the [multilib] section in /etc/pacman.conf:

Testing repositories

Be careful when enabling the testing repositories. Your system may break after performing an update. Only experienced users who know how to deal with potential system breakage should use it.

If you enable testing, you must also enable community-testing. If you enable any other testing repository listed in the following subsections, you must also enable both testing and community-testing.

testing

This repository can be found in .../testing/os/ on your favorite mirror.

testing contains packages that are candidates for the core or extra repositories.

New packages go into testing if:

They are destined for the core repo. Everything in core must go through testing

They are expected to break something on update and need to be tested first.

testing is the only repository that can have name collisions with any of the other official repositories. If enabled, it has to be the first repository listed in your /etc/pacman.conf file.

Note:testing is not for the "newest of the new" package versions. Part of its purpose is to hold package updates that have the potential to break the system, either by being part of the core set of packages, or by being critical in other ways. As such, users of testing are strongly encouraged to subscribe to the arch-dev-public mailing list, watch the testing repository forum, and to report all bugs.

community-testing

This repository is similar to the testing repository, but for packages that are candidates for the community repository.

multilib-testing

This repository is similar to the testing repository, but for packages that are candidates for the multilib repository.

gnome-unstable

This repository contains testing packages for the next stable or stable release candidate version of the GNOME desktop environment, before they are moved to the main testing repository.

To enable it, add the following lines to /etc/pacman.conf:

[gnome-unstable]
Include = /etc/pacman.d/mirrorlist

The gnome-unstable entry should be first in the list of repositories (i.e., above the testing entry).

Disabling testing repositories

If you enabled testing repositories, but later on decided to disable them, you should:

Remove (comment out) them from /etc/pacman.conf

Perform a pacman -Syuu to "rollback" your updates from these repositories.

The second item is optional, but keep it in mind if you notice any problems.

Staging repositories

Warning: Do not enable the staging repositories for any reason. Your system will unquestionably break after performing an update. This repository is only meant for backend developer use.

This repository contains broken packages and is used solely by developers during rebuilds of many packages at once. In order to rebuild packages that depend on, for example, a new shared library, the shared library itself must first be built and uploaded to the staging repositories to be made available to other developers. As soon as all dependent packages are rebuilt, the group of packages is then moved to testing or to the main repositories, whichever is more appropriate.

Historical background

Most of the repository splits are for historical reasons. Originally, when Arch Linux was used by very few users, there was only one repository known as official (now core). At the time, official basically contained Judd Vinet's preferred applications. It was designed to contain one of each "type" of program -- one DE, one major browser, etc.

There were users back then that did not like Judd's selection, so since the Arch Build System is so easy to use, they created packages of their own. These packages went into a repository called unofficial, and were maintained by developers other than Judd. Eventually, the two repositories were both considered equally supported by the developers, so the names official and unofficial no longer reflected their true purpose. They were subsequently renamed to current and extra sometime near the release version 0.5.

Shortly after the 2007.8.1 release, current was renamed core in order to prevent confusion over what exactly it contains. The repositories are now more or less equal in the eyes of the developers and the community, but core does have some differences. The main distinction is that packages used for Installation CDs and release snapshots are taken only from core. This repository still gives a complete Linux system, though it may not be the Linux system you want.

Some time around 0.5/0.6, there were a lot of packages that the developers did not want to maintain. Jason Chu set up the "Trusted User Repositories", which were unofficial repositories in which trusted users could place packages they had created. There was a staging repository where packages could be promoted into the official repositories by one of the Arch Linux developers, but other than this, the developers and trusted users were more or less distinct.

This worked for a while, but not when trusted users got bored with their repositories, and not when untrusted users wanted to share their own packages. This led to the development of the AUR. The TUs were conglomerated into a more closely knit group, and they now collectively maintain the community repository. The Trusted Users are still a separate group from the Arch Linux developers, and there is not a lot of communication between them. However, popular packages are still promoted from community to extra on occasion. The AUR also allows untrusted users to submit PKGBUILDs.

After a kernel in corebroke many user systems, the "core signoff policy" was introduced. Since then, all package updates for core need to go through a testing repository first, and only after multiple signoffs from other developers are then allowed to move. Over time, it was noticed that various core packages had low usage, and user signoffs or even lack of bug reports became informally accepted as criteria to accept such packages.

In late 2009/the beginning of 2010, with the advent of some new filesystems and the desire to support them during installation, along with the realization that core was never clearly defined (just "important packages, handpicked by developers"), the repository received a more accurate description.